In The religion within the limits of mere reason, Kant realizes a deep critic of the religious phenomenon: he purifies the religion of foreign elements, emphasizes the relevance of moral and, finally, reduces it only to moral. The article describes these analysis and confirms it by an investigation in the personal position of Kant on religion in general and specifically on Christianity which shows not only lack of interest but hostility. In the conclusions the author discuss the need and sense of the kantian reduction to moral and affirms that, although there are interesting ideas in the kantian position, his more radical points are not valid for a pluralistic society with an evolved religious model.